This analysis of 3 large cohorts of patients with prior stroke or TIA was undertaken to explore an a priori hypothesis (ie, the hypothesis was generated from published studies1–11 before the epidemiological data were analyzed) that exposure to an inhibitor of HDAC, in the form of SVA, may be associated with a lower risk of recurrent stroke compared with nonexposure or to exposure to other AEDs. Here, HDAC9 is linked to transient ischemic attack.